Shaped charge

ABSTRACT

A shaped charge which has as an improvement a layer of fine quality explosive positioned between the normal bulk explosive charge and liner thereby providing a detonating front which exhibits a low degree of turbulence along the interior wall of the metallic liner which makes a better shaped charge for use in precision metal deformation and other uses.

]March 20, 1973 United States Patent 1 McEwan et al.

102/27 X ...l02/24 HC 102/24 HC [54] SHAPED CHARGE 2,999,743 9/1961 Breza et 3 154014 10/1964 Dunne [75] Inventors: William S. McEwan; Herbert Dean y both of china Lake Calif. 3,443,518 5/1969 Cross.........

[73] Assignee: The United States of America as Primary Examiner-Verlin R. Pendegrass represented by the Secretary of the Attorney-Edgar J. Brower and Roy Miller Navy [57] ABSTRACT A shaped charge which has as an improvement a layer [22] Filed: March 19, 1969 Appl. No.: 808,706

of fine quality explosive positioned between the normal bulk explosive charge and liner thereby providing 102/24 HC a detonating front which exhibits a low degree of tur- /0 bulence along the interior wall of the metallic liner [58] Field of Search HC [52] US. Cl. [51] Int.

which makes a better shaped charge for use in precision metal deformation and other uses.

2 Claims, 1 Drawing Figure References Cited UNITED STATES PATENTS 2,992,087 7/1961 Fassnacht et al. ..................l02/27 X PATENTEUMARZO 3975 I 3,721,192

ll 4 V 4 V V 4 4 l3 V 4 1 4 V V4 V v V 4 V V V 4 V 4 A 4 v V 4 v A V q V 4 V V 4 V 1 1 4 4 A04 V V 4 4 V 4 V 4 1 V V 7 q 4 4f v V p or J; 4 v 4 i :7? V 9 V92: P V 11" q P '6 Q 1P INVENTORS. WILLIAM 8. MC EWAN HERBERT DEAN MALLORY ROY MILLER ATTORNEY.

SHAPED CHARGE GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION It is well known that FIGURE Monroe or shaped charge effect is one of the most striking means of perforating steel casings and deforming metal. A shaped charge consists of an explosive backed liner and comes in such basic geometries as the cylindrical shaped charge and the linear shaped charge. Detonation of the explosive permits the explosion products, on collapse, to form a well organized, high-velocity jet capable of exerting .intense pressure against any surface with which the charge may be in contact. Prior art discloses that explosive mixtures containing large particles are generally used in shaped charges because manufacturing techniques dictated that the mixture be pourable in the molten state. However, in copending application Ser. No. 734,188 filed May 29, 1968, it is disclosed that shaped charge devices with warheads comprising explosives having particle size ranging less than 200a (0.05 to 200p.) showed that a smoother detonation front striking a shaped charge liner minimizes distortion during jet formation, thus making these shaped charges more efficient. -According to the aboveidentified application greater effectiveness was realized with the use of the high quality detonatable explosive having particles no longer than about 20011.. This quality explosive is expensive and not easy to fabricate. The present improved shaped charge slows down the high degree of turbulence along the interior wall of the conventional shaped charge liner and yet permits the use of cheaper and more easily available bulk high explosive materials for the body of the shaped charge. This shaped charge is capable of cutting deep, small diameter holes in steel or other materials.

DESCRIPTION OF THE DRAWING The single FIGURE is a longitudinal cross-section of a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE INVENTION Referring now to the single feature there is shown a cross-section of a shaped charge which comprises a cylindrical housing 11 adapted to confine an explosive detonator 12 in one end, and containing an explosive charge 13 which has a concave cavity 14 oriented toward the open end of housing 13. A metallic liner 15 is superimposed over said concave cavity 14, and a layer of a fine explosive 16 (ranging in thickness from about one-fourth to one-half inch or as determined by the composition of the explosive charge and the metal used as liner) is positioned between said liner 15 and said explosive charge 13.

The explosive which makes up the main explosive charge 13 consists of a commercial grade explosive composition selected from the group consisting of HMX, PETN, RDX, or Composition B (55.2 percent RDX, 40 percent TNT, 1.2 percent polyisobutylene and 0.6 percent wax). Other suitable castable explosives such as pentolite and ednatol may be used. The metallic liner 15 in the form of a truncated cone is desirably of a substance which is a poor conductor or transfer agent of the shock wave. Zinc, lead, cadmium and copper are among the suitable materials used. Liner 15 is ordinarily placed contiguous with the concave cavity of the explosive charge 13. In the present invention, the interior wall of liner 15 is coated with a fine quality explosive 16 ranging from /1 to /z-inch in thickness and then positioned contiguous with the explosive charge 13. Fine quality explosive means for purposes of this invention a homogeneous mixture of very finely ground crystals of high explosive compounds suspended in an isotropic media.

The inventors discovered that a thin layer of fine quality explosive, that is, a fine crystalline high explosive composed of particles ranging in size from 200p or less in a binder positioned immediately next to the shaped charge liner smoothed out or lowered the degree of turbulence along the interior wall of the shaped charge liner, thereby improving the results of the shaped charge for precision metallic deformation and other shaped charge application. Explosives used for coating or covering the interior wall of liner 15 included Detasheet, a tradename product, comprising 85 percent PETN of 200p. or less and a 15 percent rubbery binder; a mixture comprising 95.84 percent TNT and 4.16 percent RDX granules, 200p. or less; or a mixture comprising percent HMX granules, 200p. or less, and 25 percent TNT. In the preparation of these fine quality explosive formulations containing TNT and HMX or RDX, the TNT is melted and the powdered HMX or RDX (200p. or less particle size) is mixed into the molten TNT. The molten mixture is then cast over the interior portion of the metallic liner 15 to a depth ranging from A to /-inch, or as determined from the bulk explosive used for the detonatable charge 13 and the material used for liner 15. The coating or layer 16 is allowed to cure and the predetermined amount of bulk explosive charge 13 of varying granular size is cast next to said coating or layer 16.

The fine quality high explosive used for layer 16 on the interior wall of the metal liner may be sprayed on, dipped, or pressed on. Special explosive formulations may be made up for this particular application so as to maximize the desired effect. As hereinbefore set out they are a homogeneous explosive material containing very finely ground crystals suspended in an isotropic media. This invention allows for the use of cheaper or more easily fabricated and perhaps less sensitive explosives in the bulk charge, and conversely, a more sensitive explosive can be used in the explosive layer next to the liner since it would be protected by the metal liner on one side and the bulk of the less sensitive explosive on the other side.

What is claimed is:

l. A shaped charge comprising a housing adapted to confine an explosive detonator and having an open end;

a detonatable explosive charge positioned within said housing having a concave cavity oriented toward said open end of said housing; said charge comprising a member selected from the group consisting of HMX, PETN, RDX, pentolite, ednatol and Composition B;

wherein said charge consists of Composition B; said liner consists of copper; and said layer consists of about percent by weight PETN having a particle size of about 200;; suspended in about 15 percent by weight rubbery binder. 

1. A shaped charge comprising a housing adapted to confine an explosive detonator and having an open end; a detonatable explosive charge positioned within said housing having a concave cavity oriented toward said open end of said housing; said charge comprising a member selected from the group consisting of HMX, PETN, RDX, pentolite, ednatol and Composition B; a metallic liner superimposed over said concave cavity; and a fine grade explosive layer of predetermined thickness positioned between said liner and said detonatable explosive; said layer consisting essentially of a high explosive compound having a particle size of about 200 Mu suspended in an isotropic media.
 2. The shaped charge in accordance with claim 1 wherein said charge consists of Composition B; said liner consists of copper; and said layer consists of about 85 percent By weight PETN having a particle size of about 200 Mu suspended in about 15 percent by weight rubbery binder. 